This function can be used to update the size in the "reg" property
of the NOR FLASH device nodes. This is necessary for boards with
non-fixed NOR FLASH sizes.

Signed-off-by: Stefan Roese <sr@denx.de>
Acked-by: Gerald Van Baren <vanbaren@cideas.com>
Acked-by: Wolfgang Denk <wd@denx.de>